ldhflyguy Loc: near Chicago

I've read many times that if I use my Nikon D800 set to DX and use my FX lenses their focal length is multiplied by 1.5. So, my 70 - 200mm lens becomes a 105 - 300mm lens. That sounds a lot better to me than buying a 300mm lens.
What are some of the downsides? I'm mainly concerned about image quality and cropping.

chase4 Loc: Punta Corona, California

Check out how many fewer pixels you'll get in DX. I suggest you run a test of both FX and DX from your camers and then be the judge.
chase

FJT Loc: Delaware

Your 800 has 36 megapixels and the largest dx that nikon makes, (The 7200) has 24 megapixels. So you're really not gaining anything.

The other issue is that your 70-200 mm lens, doesn't change focal lengths, it just captures less of the image on the DX sensor so you might as well just crop the image in post.

ldhflyguy Loc: near Chicago

Thank You Chase.
I've seen that there will be fewer pixels; but, I've assumed that the pixels will be around the perimeter of the FX picture that I normally get. Since I'm using the DX view on my viewfinder I can see ahead of time what would be missing from an FX picture.
I've tried some testing in my basement using a target and looking at the results on my monitor. I'm finding that there are very little quality losses; but, I'm pretty sure that isn't going to be true in real world testing.

I've used a teleconverter on my 70-200mm and can definitely see some losses.
So, I'm wondering if shooting DX through my D800 is a better idea based on other peoples opinions.
And, what are the downsides to shooting DX through my D800?

ldhflyguy Loc: near Chicago

Sadly that all makes sense. And, I know what cropping can do to the quality of a photo. So, I guess buying a good 300mm FX lens is the only way to get good 300mm photo. Switching my camera to DX isn't really that helpful.

Kookuck Loc: Cleveland Ohio0

Smaller sensor size. Your Fx images are going to be able to make prints with more detail. Dx does have advantages for shooting wildlife though.

jackpi Loc: Southwest Ohio

Your image will be 15Mp.

ldhflyguy Loc: near Chicago

I'm wanting to shoot more bird photos.
That's what got me started with trying to extend my range using Dx on an Fx camera and not buying more lenses.
Please tell me more.

alandg46 Loc: Boerne, Texas

Just crop them to a DX. Don't deliberately convert your 36 megapixel camera to 15. Maybe you won't be able to see the framing, but you'll have lots of room to play.

Kookuck Loc: Cleveland Ohio0

I started out in the film days. If you ever see a picture of Ansel Adams working he was shooting with an 8" X 10" camera. That is because in the 30's & 40's film emulsions weren't that good. Their resolving power to capture more detail increased by leaps & bounds so we were able to get nice images from a 35 MM camera. It is the same with sensors. the more pixels you have the greater detail you can capture. The Hasselblad digital camera will give you more detail than a standard "35 MM style" DSLR because it's sensor is so much bigger. If i were shooting a film negative on today"s emulsions today with an 8" x 10"camera I could make a print big enough to cover a wall. if your prints are going to be 8" x 10" or 8 !/2"
X 11" you will likely be OK with a DX format. Any bigger and I would stick with the FX. Tele-extenders are a relatively inexpensive way to get more reach. The choice is yours though. Try out the DX sensor size and see what you think.

Reinaldokool Loc: San Rafael, CA

I am an FX (FF) skeptic. I think that for most of us, the DX sensor is fine. The cameras are lighter in weight, less expensive, etc. The images are excellent and I regularly print 16x24 and 20x30. For a few people, the slightly less noise at high ISO and the depth of field make it worthwhile.
However. . .

Now that you have put out all that money, and weight-lifting, why would you give up those advantages? Cropping on your computer is easy and you will still have the larger RAW file to go back later, if you wish, and take advantage. That just seems a no-brainer. Back in the day when memory cards were small and cameras slower and a small hard drive cost $400 the smaller files were helpful, but now, I see no advantage in throwing away pixels and the other advantages ahead of time.

moonhawk Loc: Land of Enchantment

As another poster said, cropping your D800 to a DX frame will get you only about 15 MP. On the other hand, buying a DX camera body, will get you the same image, but with 24 MP instead of 16.

However, for birds, 300mm isn't going to be that big an improvement. Think about getting the 200-500 f/5.6, or one of the Sigma or Tamron 150-600 lenses. I shot recently an 800 mm equivalent combination, and you still need to get closer to the bird. Technique and patience ar your best friends.

bpulv Loc: Buena Park, CA

Using an FX lens in the DX mode makes no sense at all because you will gain nothing. In DX mode, your camera is using only a portion of the sensor that restricts the resolution to about 16Mp. That is equal to the resolution you will have by cropping a picture taken in the FX mode to match the DX mode picture area. I.e., you will end up using the same number of pixels and, therefore have the same resolution either way. I have the f2.8 24-70mm lens and because of the 36Mp starting resolution am able to get sharp high quality photographs by cropping to a point that I am using less than the DX portion of the sensor. If you are making big enlargements and need high resolution, you should invest in an appropriate focal length FX lens and forget about playing games.

ldhflyguy Loc: near Chicago

Wow!
So many nice people.
Thank You... to all of you.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Using DX crop gives you the same result as cropping in post. No advantage as far as image quality is concerned. You are taking a camera that provides a 7,360 x 4,912 px image and turning it into one that only gives you 4,800 x 2,704 px, or 15.3 mp. If you routinely already crop your images, your image quality will not change - you'll just have fewer cropping options.

As far as you lens is concerned, you still have a 70-200, only using that smaller part of the center of the image as recorded by the sensor. The only advantage is you can shoot at 5 fps instead of 4 with the standard battery, or if you have a MB-D12 and either the alkaline battery tray or the EN-EL18 battery and BL-5 cover you can go to 5 fps.

A better option if you have the battery grip is to go to 1.2 format. You will still get a bump in FPS - to about 5 - and a bigger image - 6,144 x 4,080 px or 25mp.

It's hard to compose in the cropped view, especially if you have a lens with a small maximum aperture. All you get are guide lines, so you actually see the entire D800 frame, with the crop lines superimposed.

The 70-200 VRII does a very decent job with the 1.4 and the 1.7 TC, but you will get even better performance if you get the 200-500, and better yet if you get the 150-600 Tamron G2 or the Sigma Sport.

There is no magic shortcut to great image quality - you have a camera that can capture great resolution, now you just need to decide which of the long lenses you are going to get. Forget about a 70-300 - if you are happy with the 70-200, but not thrilled when you add a 1.4 TC, you won't be happy at all with the 70-300.

This is an image taken with a Sigma Sport at 600mm, using a D800, and cropped down to 3.9 mp (1747x2236). I made a print at 72 ppi for a finished image size of 24x31 (roughly) and it looked very crisp. Of course you will see flaws and softness if you hold it 10 inches from your face and use a loupe, but hanging on a wall, in a frame, with a nice 2" border around it, and viewed at a normal viewing distance of 4 ft or so, (1.5x the diagonal dimension), it's just fine and no one will complain that it isn't sharp.

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